Single-Photodiode Optical Receiver for TE/TM Signal Combining
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Solution Overview
Problem
Existing optical receivers face issues with return light destabilizing optical communication systems, increased parasitic capacitance leading to reduced response speed, and high power consumption due to the use of separate photodiodes for detecting different polarization components, and complex manufacturing processes when using photodiodes above grating couplers.
Innovation Solution
An optical detection device and receiver that uses a single photodiode to combine the intensity of TE and TM polarization components, reducing return light and parasitic capacitance by configuring the photodiode to absorb light over a long distance with strained germanium on silicon, and avoiding the need for additional circuits to sum electrical signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate photodiodes are used to detect different polarization components, then detection accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent merges the detection of TE and TM polarization components into a single photodiode by combining their optical paths in a light-receiving waveguide. The first and second optical signals (corresponding to different polarizations) are combined and incident on one photodiode, eliminating the need for separate photodiodes while maintaining detection capability through optical path integration
Solution Approach 2:
The single photodiode is designed to handle multiple functions: detecting both TE and TM polarization components, receiving combined optical signals from multiple waveguides, and operating with reduced return light effects. This multi-functional design replaces what would traditionally require multiple specialized components
2Measurement precision
If separate photodiodes are used to detect different polarization components, then detection accuracy is improved, but power consumption increases
Solution Approach 1:
The patent combines the optical paths of TE and TM polarization components into a single light-receiving waveguide that feeds one photodiode. This merging eliminates the need for multiple photodiodes and their associated readout circuits, directly reducing power consumption while maintaining the ability to detect both polarization components
3Ease of manufacture
If photodiodes are placed above grating couplers, then manufacturing is simplified, but return light increases destabilizing the system
Solution Approach 1:
The patent extracts and eliminates the harmful return light effect by introducing a return light reduction structure between the light-receiving waveguide and the photodiode. This structure specifically targets and removes the detrimental reflected light while preserving the beneficial combined optical signals, thereby maintaining manufacturing simplicity while improving system stability
Solution Approach 2:
The patent converts the harmful return light (reflected light from the photodiode back through the waveguide) into a beneficial configuration by using a return light reduction structure that allows the main optical signals to pass through while blocking only the harmful reflected components. This transforms a potentially destabilizing effect into a controlled element that does not interfere with system operation
4Device complexity
If a single photodiode is used to combine polarization components, then device complexity is reduced, but return light increases destabilizing the system
Solution Approach 1:
The patent extracts and removes the harmful return light effect by introducing a dedicated return light reduction structure in the light-receiving waveguide. This structure selectively eliminates reflected light that would otherwise destabilize the system while preserving the functional benefits of using a single photodiode
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables a polarization-independent optical receiver with high-speed operation and low power consumption, improving system reliability by minimizing return light and circuit complexity, while allowing the use of standard photodiodes on silicon waveguides.
Implementation Method 1
uses a single photodiode to combine the intensity of TE and TM polarization components, reducing return light and parasitic capacitance by configuring the photodiode to absorb light over a long distance with strained germanium on silicon
Data Source
AI summary
Provided is an optical detection device that includes a light-receiving waveguide and a light-receiving unit. The light-receiving waveguide is connected to a first input waveguide to which a first optical signal is input and a second input waveguide to which a second optical signal is input. The light-receiving unit is configured to output an electrical signal corresponding to an intensity of a signal obtained by combining the first optical signal and the second optical signal input to the light-receiving waveguide. The light-receiving unit is configured to reduce an intensity of an optical signal returning in an opposite direction from a first direction in which the first optical signal propagates in the first input waveguide, and an intensity of an optical signal returning in an opposite direction from a second direction in which the second optical signal propagates in the second input waveguide.